Network instant messaging tools developed until today, have been accepted by the majority of the internet users and become indispensable software tools for the users. The network instant messaging tools have been widely used not only in daily entertainments but also in user's working. The instant messaging software can provide more and more functions, and these functions are also gradually maturing. At the same time, in the social networks service (SNS) formed among online users, it is no longer just an individual user's relationship with a single user, but one-to-many and many-to-many relationships. The social networks include online users and their relationship networks, have a very great value, enable accurate search and transmission of information, and meet the different needs of users and businesses.
The SNS network includes mass users and mass relation data, thus a basic problem to be solved is how to find out valuable and interesting information from the mass data of the SNS network. Obviously, not all the mass users and mass relation data of the SNS network are concerned by the individual users or the business users, the individual users or the business users are interested in relationship circles of specific targets.
Most of the existing SNS websites support the search for network members by keywords, the search results can show every person who can meet the designated features but cannot show relationship among these persons and relationship circles defined by them, and cannot analyze and extract relationship circles of special targets. Therefore, more valuable relationship information cannot be found.